How to Start a Colorado LLC: Step by Step

Your LLC name has to be distinguishable from every other business name already on file with the Colorado Secretary of State. "Distinguishable" is a legal test, not a gut feeling: two names that differ only by punctuation, spacing, or a filler word like "the" can still be treated as the same, and the state will reject a filing that clashes.

Run your proposed name through the Colorado business database search before you do anything else. Search the exact name and a few close variants. If something too similar already exists, adjust before you file rather than after.

Colorado naming rules

• The name must include one of the terms the Secretary of State's checklist lists: limited liability company, ltd. liability company, limited liability co., ltd. liability co., limited, l.l.c., llc, or ltd.
• It must be distinguishable on the record from all existing Colorado entity names.

Reserving a name

Not ready to file today? Colorado lets you reserve an available name online for $25, which holds it for 120 days while you sort out the rest, and you can renew for another $25. Reservation is optional. If you're ready to file now, the name locks in the moment your Articles are accepted.

Trade names (DBAs)

Planning to operate under something other than your exact legal name? You register a trade name with the Secretary of State as a separate filing. For an LLC in good standing, a Colorado trade name does not need to be periodically renewed, which is unusual and worth knowing. The trade name process is distinct from forming the LLC itself.

Before you open the Articles of Organization, decide who your registered agent will be. You name them right in the filing, and they must consent to the role.

Colorado requires every LLC to keep a registered agent with a physical address in Colorado for as long as the company exists. The agent receives lawsuits, subpoenas, and official state mail on behalf of the LLC, so the Secretary of State won't accept a P.O. box or commercial mailbox address as the agent's street address.

Who can serve

• You: if you're over 18, your primary residence or usual place of business is in Colorado, and you hold a valid Colorado driver's license or ID card (or verify your residency with the Secretary of State). That ID rule came from 2024 changes to Colorado law. Your address will appear in the public record.
• A trusted individual: anyone who meets those same tests, such as a co-owner, employee, or attorney.
• A business entity in good standing: this is what a commercial registered agent service is. It puts its own professional address on the public record in place of yours.

Your new LLC can't name itself at formation. The state allows an LLC to become its own agent only after it is registered, by filing a change later.

Why the choice matters

Use your home as the agent address and it becomes searchable on the Secretary of State's site, indexed and permanent. A lot of owners choose a commercial service precisely to keep a home address private, and to avoid the compliance risk of missing a hand-delivered legal document because they were on vacation or out on a job.

The Articles of Organization is the filing that brings your LLC into legal existence. In Colorado you file it online through the Secretary of State's Business Division. There is no paper path for LLC Articles. The state fee is $50, paid online by credit card, debit card, or prepaid account.

Colorado processes online filings in real time, and without a delayed effective date your filing takes effect immediately after payment. A filing that names an individual agent who lacks a Colorado driver's license or ID is the exception: it goes into a review queue first. Once accepted, your LLC shows up immediately in the public database and your filed document is available to download.

What the Articles ask for

• LLC name with its required designator
• Principal office street address, which is public
• Mailing address (a P.O. box is fine here)
• Registered agent's name, Colorado street address, and mailing address, plus their consent to serve
• Management: whether managers or members run it, and a statement that there is at least one member
• The person forming the LLC: name and address of each, who must be 18 or older if an individual
• Optional: attachments and a delayed effective date up to 90 days out

Colorado requires written consent before you list any other person's name or address in a filing, so check with your agent and anyone else you name first.

Take a minute to proofread before submitting. Because approval is instant, a typo in your name or agent address becomes part of the official record immediately and takes a separate corrective filing to fix.

Once Colorado has accepted your Articles, apply for an Employer Identification Number from the IRS. The EIN is your business's federal tax ID: the number a bank asks for to open a business account, that you use on tax filings, and that you give to payroll if you hire.

You apply directly with the IRS, not with Colorado, and the fastest route is the free online EIN application. When you complete it online during operating hours, the IRS issues the number on the spot. A single-member LLC with no employees can technically use the owner's Social Security number for some purposes, but getting an EIN is still smart. It keeps your SSN off business paperwork and is required the moment you add employees or elect corporate taxation. Note that the ID number Colorado assigns your LLC is not your EIN. If Mainstay forms your LLC, we apply for the EIN for you; the IRS charges nothing for it either way.

Before you apply

• Have your approved Colorado LLC on file first: the EIN application asks for the legal name and formation state.
• Know your responsible party (usually a member) and their SSN or ITIN.
• Decide your default tax classification; you can layer an S-corp election on later if it makes sense.

Colorado does not require you to file an operating agreement, and the statute technically permits an oral one, but a written agreement is one of the most valuable documents your LLC will ever have, and you create it yourself rather than filing it with the state.

The operating agreement is the internal rulebook. It sets out who owns what percentage, how much each member contributed, how profits and losses are divided, who has authority to sign and make decisions, how new members come in, and what happens when a member wants out or the company winds down. For a multi-member LLC it is essential; for a single-member LLC it still reinforces the separation between you and the business that Colorado courts examine when liability protection is challenged.

Without a written agreement, the default provisions of Colorado's LLC Act govern everything by law, and those defaults, such as splitting profits and voting power in ways you may not intend, are rarely a perfect match for a real business.

With your Articles accepted and your EIN in hand, open a dedicated business bank account before you take in a dollar of revenue. A separate account is the single most important habit for preserving liability protection, because commingling personal and business money is the fastest way to give someone grounds to disregard the LLC. Bring your filed Articles, your EIN confirmation, and your operating agreement; most banks want all three.

Ongoing Colorado compliance

• Periodic Report: file it online with the Secretary of State once a year for $25, any time from two months before to two months after your LLC's periodic report month (shown on its summary page). It confirms your agent and principal office; it is not a financial filing. Missing it means a $50 late penalty, then Delinquent status, which takes a $100 Statement Curing Delinquency to fix.
• Registered agent: keep a valid Colorado agent and address on file at all times, and update the record promptly if either changes.
• State and local licensing: check whether your trade needs state licensure and whether your city requires a business license or a sales tax license. Colorado has no single statewide general business license.
• Taxes: file federal returns per your classification and account for Colorado's flat state income tax; register for state sales tax if you sell taxable goods or services.

Handle these and your LLC stays active and in good standing year after year, which is exactly the point of forming one in the first place.